Cab-Tilt System 60 - American LaFrance Aftermarket Parts

[Pages:59]Cab-Tilt System

60.00

General Information

General Information

The cab-tilt system has three major parts:

? A hydraulic pump consisting of a pump body, a reservoir, and a pump control lever.

? A hydraulic tilt cylinder that raises and lowers the cab.

? A tilt safety stop on the tilt cylinder, which must be used when working under a cab that has not been fully tilted.

The cab can be tilted open to 42 degrees to access the engine and other components. A hydraulic pump, located behind the right side of the cab, is used to operate the hydraulic cab tilt mechanism. See Fig. 1.

The tilt cylinder is connected to the pump by flexible high-pressure lines. Velocity fuses are built into the tilt cylinder port. They act as check valves to prevent the cab from free falling in case of hydraulic system damage, such as a ruptured line.

Hydraulic Lock-Up

Hydraulic lock-up can occur for the following reasons:

? Very cold weather

? Use of the wrong hydraulic fluid

? Air in the system

? Sudden cab movement

? A ruptured hydraulic line

Any of the above situations will cause the velocity fuses to function as safety check valves, and lock up the tilt cylinder. To unlock the cylinder, the cab must be moved in the opposite direction of travel.

IMPORTANT: If the tilt cylinder locks up, check for a major problem (such as a ruptured line or leaking fitting) before trying to unlock the tilt cylinder. If such a problem is found, make any necessary repairs before unlocking the cylinder.

For example, if the cab is moving toward the full-tilt position when the lock-up occurs, move the control lever to RETURN, and work the pump a few strokes. This will unlock the cylinder. Move the control lever to TILT, and allow the cab to descend to a full-tilt position.

If the cab is moving toward the lowered (operating) position when the lock-up occurs, move the control lever to TILT, and work the pump a few strokes. This will unlock the cylinder. Move the control lever to RETURN, and allow the cab to descend to the operating position.

06/23/2000

f880505

Fig. 1, Cab Tilt Pump

NOTE: Whenever raising or lowering the cab, stop working the pump once the cab goes over center. The cab falls at a controlled rate and continued pumping could lock up the tilt cylinder. To slow the descent of the cab, reverse the lever.

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Cab-Tilt System

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Cab Tilting

Tilting the Cab

CAUTION

Before tilting the cab, make sure the vehicle is parked on level ground, both side-to-side and front-to-rear. Tilting the cab while the vehicle is parked on uneven ground (such as a sloping highway shoulder) may damage the cab mounts and prevent you from returning the cab to the operating position.

WARNING

Before tilting the cab, make sure there is adequate clearance in front of the vehicle, and that the area is free of people and all objects.

Do not tilt the cab with the engine running. Tilting the cab could engage the transmission. If the engine is running, the vehicle can move, causing an accident that could result in personal injury or property damage.

IMPORTANT: Before raising or lowering the cab, read the warning label on the hydraulic pump.

1. Park the vehicle on a level surface, apply the parking brakes, shut down the engine, and chock the rear tires.

2. Secure all loose articles in the cab and make sure the doors are securely latched.

WARNING

Objects falling in the cab, or a door flying open, could damage the vehicle or cause personal injury.

3. Make sure there are no people or objects in the path the cab will be traveling.

4. Move the pump control lever to TILT position.

5. Remove the pump handle from behind the primary driver's seat and attach it to the pump.

6. Raise and lower the pump handle several times to unlock the cab mounts.

IMPORTANT: Check the indicator pin on each cab latch. The latches have disengaged if the pins are out. See Fig. 1.

NOTE: If air is present in the hydraulic tilt system, the pump operation may seem spongy or ineffective. If this happens, bleed the air from the system. See Subject 100 for instructions.

7. Continue to operate the pump handle until the cab is tilted open about 30 degrees.

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f310441

Fig. 1, Cab Mount Indicator Pin

IMPORTANT: If the cab stops moving while it is being raised, do not force it to move with the tilt pump. The velocity fuses have locked up the tilt cylinder. To unlock the tilt cylinder, see "Hydraulic Lockup of Cab Tilt System", in Subject 050.

8. Put the safety stop on the tilt cylinder in place.

The safety stop prevents the cab from dropping below a specific angle. See Fig. 2.

DANGER

Make sure the tilt safety stop is pushed down onto the tilt cylinder rod. If the tilt safety stop is not engaged, and the cab drops, the result could be serious injury or death.

9. Continue to operate the pump handle until the cab has reached the 42-degree, fully open position.

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Cab Tilting

Cab-Tilt System

1 2

1

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1. Tilt-Cylinder Rod 2. Tilt Safety Stop

Fig. 2, Tilt Safety Stop Positioning

Lowering the Cab

f310357a

DANGER

Stay completely clear of the cab's travel path at all times. Once the tilt safety stop has been released, do not lean over the frame rails, the engine, or the transmission for any reason. To do so could result in serious injury or death.

1. Secure all loose articles in the cab and make sure the doors are securely latched.

2. Make sure the parking brakes are applied and there are no obstructions in the cab travel path.

3. Lift the safety stop up until it no longer rests on the tilt cylinder rod. See Fig. 3. The cab may need to be raised if the safety stop is resting against the tilt cylinder rod.

4. Move the pump control lever to the RETURN position. The cab will automatically begin to return to the operating position.

NOTE: To slow the descent of the cab, reverse the tilt pump lever.

5. After the cab is completely lowered, check the indicator pin on each cab mount. The cab mounts are locked when the pins have moved back into the piston and the cylinder spring assembly. If the pins are out, the cab mounts are not locked. See Fig. 1. Raise and lower the

3 2

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1. Tilt Safety Stop 2. Tilt-Cylinder Rod 3. Tilt Cylinder

f310358a

Fig. 3, Releasing the Tilt Safety Stop

pump handle until the cab is completely lowered and the cab mounts are locked.

IMPORTANT: If the cab stops moving while it is being raised, do not force it to move with the tilt pump. The velocity fuses have locked up the tilt cylinder. To unlock the tilt cylinder, see "Hydraulic Lockup of Cab Tilt System", in Subject 050.

6. Make sure the pump control lever is in the RETURN position.

7. Remove the pump handle and return it to its stored location.

8. Remove the chocks from the tires.

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Cab-Tilt System

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Bleeding the System

Bleeding the System

A "spongy" feeling (cylinders do not move when the pump handle is operated) indicates air in the cab-tilt system. Use the following procedures to remove the air from the cab-tilt system.

IMPORTANT: With the exception of bleeding the pull port fittings on the tilt cylinders, and the hydraulic cab latches, never bleed any part of the system while the cab is tilted.

Bleeding the Tilt Cylinder

DANGER

Before doing the work below, review the cab tilting information in Subject 060. Failure to read the warnings and to be aware of the dangers of tilting and returning the cab could result in serious injury or death.

1. Park the vehicle on a level surface, apply the parking brakes, shut down the engine, and chock the rear tires.

2. With the cab completely returned and the tilt cylinder retracted, loosen the push port fitting on the tilt cylinder. Do not disconnect the hose from the fitting. Place the control lever in the TILT position, and operate the tilt pump until a bubblefree stream of hydraulic fluid flows from the push ports on the tilt cylinder.

3. Tighten the push port fitting on the tilt cylinder.

4. Fill the tilt pump reservoir until hydraulic fluid appears in the fill port. Install and tighten the fill plug. See Specifications, 400 for the specified hydraulic fluid. Do not use engine oil, brake fluid, or automatic transmission fluid.

5. Tilt the cab to the full-tilt position. See Subject 060.

6. Loosen the pull port fitting on the tilt cylinder. Place the control lever in the RETURN position, and operate the tilt pump until a bubble-free stream of hydraulic fluid flows from the pull port fitting on the cylinder.

7. Tighten the pull port fitting on the tilt cylinder.

DANGER

Stay completely clear of the cab's travel path at all times. Once the tilt safety stop has been released, don't lean over the frame rails, the engine, or the transmission for any reason. To do so could result in serious injury or death.

8. Return the cab to the operating position. See Subject 060.

9. Fill the tilt pump reservoir until hydraulic fluid appears in the fill port. Install and tighten the fill plug. See Specifications, 400 for the specified hydraulic fluid. Do not use engine oil, brake fluid, or automatic transmission fluid.

10. Tilt the cab fully and return it to the lowered position. See Subject 060. Fill the tilt pump reservoir until hydraulic fluid appears in the fill port. Use only specified hydraulic fluid. Install and tighten the fill plug.

Bleeding the Hydraulic Cab Latches

DANGER

Before doing the work below, review the cab tilting information in Subject 060. Failure to read the warnings and to be aware of the dangers of tilting and lowering the cab could result in serious injury or death.

Since the hydraulic cab latches are mounted higher in the system than the tilt pump, air going to them will not discharge to the reservoir.

1. Park the vehicle on a level surface, apply the parking brakes, shut down the engine, and chock the rear tires.

2. Tilt the cab to the full-tilt position. See Subject 060.

3. Push the free end of the tilt safety stop down onto the rod of the tilt cylinder.

4. Put the pump control lever into the RETURN position. Operate the tilt pump until the cab goes over-center. Let the cab settle onto the tilt safety stop.

5. Loosen the hydraulic fitting on the cab latch.

6. Put the pump control lever in the TILT position; then operate the tilt pump until a bubble-free

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Bleeding the System

stream of fluid flows from the fitting. Pump until about 2 fl oz (60 mL) of fluid flows from the fitting to ensure the entire line is free of air.

7. Tighten the cab latch fitting.

8. Put the pump lever in the RETURN position.

9. Loosen the fitting on the left cab latch.

10. Put the pump control lever in the TILT position; then operate the tilt pump until a bubble-free stream of fluid flows from the fitting. Pump until about 2 fl oz (60 mL) of fluid flows from the fitting to ensure the entire line is free of air.

11. Tighten the cab latch fitting.

12. With the pump control lever still in the TILT position, operate the tilt pump just enough to take the weight off the tilt safety stop; then release the tilt safety stop, and lock it in the spring catch.

13. Return the cab to it's normal operating position. See Subject 060.

14. Fill the tilt pump until hydraulic fluid appears in the fill port. See Specifications 400 for specified hydraulic fluid. Don't use engine oil, brake fluid, or automatic transmission fluid.

15. Install the fill plug and tighten it firmly.

16. Remove the chocks from the tires.

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Condor Workshop Manual, Supplement 0, January 2000

Cab-Tilt System

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Troubleshooting

Troubleshooting Tables

Problem--Cab Fails to Tilt or Fails to Return from Tilt When Using Manual Pump Lever, but Hydraulic Pressure Builds In System

Problem--Cab Fails to Tilt or Fails to Return from Tilt When Using Manual Pump Lever, but Hydraulic Pressure Builds In System

Possible Cause

Remedy

Cab latch binding or failing to unlatch.

Check the cab latch release mechanism.

Plugged orifice at the bottom of the spool Replace or rebuild the tilt pump. in the tilt pump.

Control lever in the wrong position.

Put the control lever in the correct position.

Worn seals or O-rings in the tilt pump.

Replace or rebuild the tilt pump.

Hoses blocked.

Replace the hoses.

Push and pull lines crossed.

Check for correct installation.

Internal leak in tilt pump.

Repair or replace the tilt pump.

Internal leak in tilt cylinder.

Repair or replace the tilt cylinder.

External leak.

Repair or replace the leaking part.

Air in hydraulic system.

Bleed the hydraulic system.

Problem--Cab Stops Moving When in Controlled Fall

Possible Cause Velocity fuses locked up.

Plugged orifice. Tilt strut left engaged.

Problem--Cab Stops Moving When in Controlled Fall Remedy

Reverse the pump direction with the control lever, and operate the pump to unlock. Inspect, and clean or replace. Disengage the tilt strut.

Problem--Cylinder Velocity Fuses Are Locked Up

Problem--Cylinder Velocity Fuses Are Locked Up

Possible Cause

Remedy

Controlled fall rate is too fast.

Inspect the orifice in bottom of spool valve; replace or rebuild the tilt pump, if needed.

Air in the system.

Bleed the system.

Ruptured hydraulic line.

Replace the hydraulic line.

Problem--Hydraulic Fluid Leaking at Hand Pump Plunger or Around Spool Valve

Problem--Hydraulic Fluid Leaking at Hand Pump Plunger or Around Spool Valve

Possible Cause

Remedy

Worn seals and O-rings.

Replace or rebuild the tilt pump.

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Troubleshooting

Cab-Tilt System

Problem--Hydraulic Fluid Leak at the Tilt-Cylinder Gland

Problem--Hydraulic Fluid Leak at the Tilt-Cylinder Gland

Possible Cause

Remedy

Worn seal on the gland.

Replace or rebuild the tilt cylinder.

Problem--Tilt Pump Leaks Between the Pump Base and the Reservoir

Problem--Tilt Pump Leaks Between the Pump Base and the Reservoir

Possible Cause

Remedy

Worn O-ring on the reservoir. O-ring on the reservoir pinched.

Replace the O-ring on the reservoir. Replace the O-ring, making sure it is properly positioned.

Problem--Cab Drifts When in the Half-Raised Position

Problem--Cab Drifts When in the Half-Raised Position

Possible Cause

Remedy

Worn spool valve seals.

Replace the spool valve seals or rebuild the tilt pump.

Worn piston seals inside the tilt cylinders. Replace the piston seals or rebuild the tilt cylinders.

Control lever not all the way in the correct Place the control lever in the correct position. position.

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Specifications

Torque Values

Description

Size

Grade

Tilt Cylinder Mounting Capscrew Tilt Cylinder Bracket Assembly Capscrew Tilt Pump Cylinder Tilt Pump Relief Valve Tilt Pump Outlet Seat Tilt Pump Reservoir Socket-Head Capscrews Push and Pull Port Fittings Tilt Pump Mounting Capscrews

5/8?11

8

5/8?11

8

--

--

--

--

--

--

1/4?20

7

--

--

3/8?16

8

Table 1, Torque Values

Hydraulic Fluid Types

Component or Usage

Fluid Type

Tilt Pump All Hydraulic Temperatures

Fluid

Hydraulic Fluid* MIL-H5606 specification, or equivalent *

* The following vendor lubricants are approved: Texaco 1537 Aircraft Hydraulic Oil 15; Union Arctic Low Pour (-65) Hydraulic Fluid 04617; Filmite 530 Hydraulic Oil

Table 2, Hydraulic Fluid Types

Torque

lbf?in (N?cm)

lbf?ft (N?m)

--

135 (183)

--

135 (183)

--

80 (108)

60 (680)

--

--

19?21 (26?28)

96 (1080)

--

96 (1080)

--

--

28 (38)

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